This invention relates to a suspension assembly for a vehicle.
The invention also extends to a suspension assembly and chassis for a vehicle and a vehicle incorporating these features.
This invention relates particularly but not exclusively to a suspension assembly for a low loading truck, e.g., which permits lowering of a load platform towards the ground for loading/unloading purposes. The load platform is then raised to the appropriate level during normal ride and travel of the vehicle. It will be convenient to hereinafter describe the invention with reference to this example application, however it is to be clearly understood that it is capable of broader application.
Trucks typically have a chassis mounted on four or more wheels. An operator""s cabin is mounted on the chassis towards the front of the vehicle and a load platform is mounted on the rear of the chassis. Typically a fuel driven engine, e.g., a diesel engine, drives steerable front wheels to move the vehicle.
Typically forklifts and other lifting devices are used for lifting loads on to the elevated load platform/tray of these trucks. This requires a large amount of work as the load platform is generally positioned a substantial height above the support surface. Further the lifting and lowering operation is a fairly hazardous operation particularly for heavy articles.
Some attempts have been made to modify trucks to ease or facilitate the loading operation. For example some trucks have tilt down tail portion which can be used to load articles on to the support surface. Articles to be loaded are pushed up or down the inclined tail portion to load the goods on to the load platform. The tail portion is then raised for normal travel and use of the truck.
Other attempts to address this problem of which the applicant is aware provide part of the load platform as an elevator such that articles may be loaded on to the elevator adjacent ground level and subsequently elevated by the elevator to the level of the load platform. The articles may then be transferred horizontally to any desired part of the load platform. Whilst such arrangements do provide some means for raising the load to load platform they do not provide a loading tray which may be readily disposed adjacent ground level to facilitate loading or unloading which is preferred.
Clearly it would be advantageous if a contrivance could be provided which enabled the load platform to be lowered for loading/unloading and then raised to its normal height for normal travel of the vehicle.
According to the present invention there is provided a lowerable suspension system for a vehicle deck comprising;
(a) a swing arm mounting a road wheel having a first end adapted for pivotal connection to the side of a vehicle deck,
(b) a tower connected to the vehicle deck adjacent a central position of the swing arm,
(c) a shackle arm pivotably connected to a second end of the swing arm and the deck, said shackle arm comprising two links joined by a neutral pivotal connection which are pivotably connected to the deck and to the second end of the swing arm,
(d) an air spring adapted to be interposed between the tower and the central portion of the swing arm, the arrangement and construction being such that in a first position with the air spring fully inflated the vehicle deck is horizontally disposed for normal travel and in a second position with the air spring deflated the deck is in a lowered position enabling loading and unloading to and from the deck from the ground to take place.
The swing arm and the links can be cranked.
The cranks of the links can be opposed.
The medial portion of the swing arm provides a seat for a lower end of the air spring.
First and second ends of the swing arm can be inclined with respect to one another at an angle between 145 and 155 degrees.
The first and second links of the shackle arms can be substantially arcuate.
Wherein the tower which provides a contact mounting surface for the top surface of the air spring is inclined at between 5 to 12 degrees from the plane of the deck.
According to a further aspect of the present invention there is provided a lowerable suspension system aforesaid and coupling means for attachment to a driver vehicle said attachment means including a pivotal connection between the driver vehicle, and means for locking and releasing the pivotal connection.